Private jets, chauffeur driven cars and even some economy flights will deposit some 35,000 people in Nebraska's largest city to make their annual pilgrimage to see Warren Buffett, the world's most famous investor and the man known to his fans as the Sage of Omaha.

But with the 81-year-old now being treated for cancer, questions are being asked about how long "Buffettpalozza" can survive and what his eventual departure will mean for Berkshire Hathaway, the investment firm he founded.

Berkshire Hathaway's annual meeting has a profound impact on Omaha. The hotels are booked out months in advance, taxis are rare, and the streets throng with wealthy investors. There are parties, discounts at Borsheims, a high end jewelry store Buffett owns, a barbecue. All ahead of a meeting in a stadium arena Saturday morning where Buffett and his curmudgeonly sidekick Charlie Munger, 88, will answer questions for about five hours.

At Gorat's, Buffett's favourite steakhouse, owner Debbie Branecki expects to serve 2,000 diners this weekend, at least five times the normal weekend.

"It's such a great event," she said. "There's nothing like it in the world. I think he really wants people to have fun."

Buffett has dined at Gorat's for decades, he likes a medium rare T-bone steak and a Cherry Coke (Berkshire owns part of Coca-Cola). He often takes his friends there. Branecki recalls spotting him and Bill Gates, Microsoft's co-founder, outside the restaurant puzzling over why Buffett's car wouldn't start. "I don't think either of them had a clue what was going on," she said. Fortunately their security were soon on hand to help.

But this year more than most Berkshire's shareholders must face an uncomfortable truth: Buffett can't go on forever.

Last month Buffett announced that he had early stage prostate cancer. He said he was told by his doctors that his condition "is not remotely life-threatening or even debilitating in any meaningful way".

Earlier this year Buffett announced that an individual had been chosen to take over for him when he can no longer handle the chief executive duties, but he didn't say who that was.

The cancer and succession news come at a time when Berkshire's share price has underperformed the stock market. Buffett, whose investments nclude American Express, Coca Cola, Tesco and a portfolio of insurance firms, has long argued against short term investments. But that argument only raises more questions about succession.

For the first time this year Buffett will be quizzed by financial analysts during the meeting as well as taking questions from the audience and from hand picked journalists. Succession is certain to be a key topic, especially as the AFL-CIO Reserve Fund, a union-affiliated Berkshire investor, has tabled a vote asking the

board to disclose its succession-planning policy.

Tim Vick, senior portfolio manager at Sanibel Captiva Trust, said Buffett's health would be the number one issue for investors this year, closely followed by succession.

"I think investors need reassuring about what is going on with him and at the company," he said.

"I think Berkshire is under valued. It's clear that the Buffett premium is gone. The market just doesn't trust his ability to pick stocks," said Vick.

In part he said this was due to Berkshire's size. The holding company is now valued at over $200bn. "Buffett has done a very good job of managing expectations in the last few years but it takes a billion dollar deal to move the needle for this company now," he said.

But there's still no doubting Buffett's long-term record.

"Over the last 45 years, the annualized return on book value [for Berkshire] has been 20% relative to say, a 9% return for the S&P 500 [Index]. So, definitely he's kind of the special sauce that makes Berkshire a wide-moat firm," wrote Gregg Warren, a senior equity analyst at Morningstar, in a research report.

And in Omaha people are hoping there's plenty of years to come for his annual jamboree. Branecki's father, Louis "Pal" Gorat, was a childhood friend of Buffett's and was offered the chance to invest in the late 1950s. He turned it down. "It was a lot of money at the time," said Branecki. It would have been a lot more now, not that she is complaining. "I don't think he's going anywhere," she said. "This is too much fun."

• This article was amended on 7 May 2012. The original incorrectly described Omaha as the capital of Nebraska.